fix only users that can edit a dashboard should be able to update panel json

public/app/core/controllers/json_editor_ctrl.ts

@@ -5,7 +5,7 @@ export class JsonEditorCtrl {
   /** @ngInject */
   constructor($scope) {
     $scope.json = angular.toJson($scope.model.object, true);
-    $scope.canUpdate = $scope.model.updateHandler !== void 0 && $scope.contextSrv.isEditor;
+    $scope.canUpdate = $scope.model.updateHandler !== void 0 && $scope.model.canUpdate;
     $scope.canCopy = $scope.model.enableCopy;
 
     $scope.update = () => {

public/app/features/dashboard/utils/panel.ts

@@ -70,6 +70,7 @@ export const editPanelJson = (dashboard: DashboardModel, panel: PanelModel) => {
     updateHandler: (newPanel: PanelModel, oldPanel: PanelModel) => {
       replacePanel(dashboard, newPanel, oldPanel);
     },
+    canUpdate: dashboard.meta.canEdit,
     enableCopy: true,
   };